Semiconductor photoelectric device



June 9, 1953 J. N. sHwE sEMc0NDUcToR PHoToELEcTRc DEvcE Filed March 21. 1951 1 atente(1 Jone 9, 193

T oFFCE AppHootion afoh 21, 1951, sofia11To. 16,75

fc1. oZ11) This iflvention felates to photosensitive sen1i oonduotof devioes and fnofe paftiou1arly t() Such devioes ino1Ilding bodieS of sen1ioonduotive fnatefio1 having oontiguous zones of opposite con ductivity types therein t iS known in the art that junctions between Bones of opposite conductivity typeS in bodies of Sen1ioonduotive nlatefio1, Suoh aS silicon and gef1I1aI1iI11T1, afo photoSensitive. ffhat iS, in known devioeS a beam of light is directed against one faoe of the body to which face fhe junction eXtends, and the cuffent obtained betfveen teI n1inalS at opposite ends of the body iS dependent upon the position of the bean1 relative to the junction. This ouffent fesu1ts ffofn the 1iberaJ- tion of ohafges Within the body by the absoTp tio11 of 1ight, and these ohafges aTe the pfinlory soufoe of the photocufrent,

The sensitivit of such known devices is lin1- ife(1 and, fufther, fepTodooibility of oharactefistioS ff()1T1 devioe to devioe is din1cu1t.

one genefa1 objoot of this invention is to at tain inlproved peffofnlanoe ohafacteristios fof SeIniconduooof photofeSponSive devices. 1`ffore speoi11o objeots of thiS invention are to iI1oreaSe the SenSitivity of such devioes to fealiZe fepfo duoib1e ohafaotefiStios thefefor, and to extend oontfo1 of the peffofInanoe pafan1eteTs.

1n one i11IlStfativo en1bodinlent of this invention, aJ photooe11 oonlpfiSes a body of gefInaniun1 119ving thefein a paif of `T conduotivitytype zones on opposite sides of and oontiguous With o Zoffe of P conduotivitytype. A soufoe iS oonnected betWeen the tWo N Zones whereby one of the P`T junotions is biaSed il1 the fevefSe difeotiof1 and the othef junotion iS biaSed in the for- Ward difection. Light is diTeoted against the P type zone, againSt one of both of the N type zones in pfoxin1ity to the P zone of against both the P zone and one of both of the 1`T Zones at fegionS in proxiInity to the P zone. T11e ab soTption of light by the body a.1ters the energy 1eve1s wh the body whefeby flow of chafge ooffiefs betWeen the tefn1ina1s is enhanced. Thus, the light oltefS the effeotive ifnpedanoe of the body and pfovides a contfo1 action upon the ourfent flow betvveen the tefInina1s.

The invention and the vafiouS featuTes thefe of vvi11 be undefStood n1ore clear1y and fu1ly ffofn the fo11owing detailed desofiptiof1 With fefefenoe to the acoofnpanying dfaWing in whioh= 1 'ig. 1 iS in paft a pefspeotive view and in paft a oifoI1it diagfan1 depictif1g one i1111Strative efn bod nent of this invention; v Figs. 2 and 3 ofe enefgy diagrafns whioh vv111 2 be fefeTred to hereinafter iI1 ana1yz1g the Inechanism of the Opefotion of the device i11uS tTated in ig. 1; and

- Figs. and 5 aTe gfaphs poffying typioa1 pefforfnance ohaTaotefistios of photoSensitive seInioondootor deviceS oonstruoted in acoordanoe with this invention.

Befeffing now to the dfaWing, the photosensitive device shovZn in 1 'ig- 1 oon1pfises a body of gernlaniun1 having two oones o and loB of 1\T conduotivitytype on oppoSite sides of and oontiguous With a thin zone of P oonduo tivity-type, the thfee zones fofming two bafTierS of junotions J1 and J2. AdvantageouSly, the body iS of Single ofySta1 stfuctufe. It olay be pfoduoed in one way in aooofdance vvith the n1ethod deScribed i11 the app1ication Seria1 1` feflo supplied to the load 13.

os Wi11 be noted hereinaftef.

168 18 1ed June 15, 1950 of (r. Te1. In al typioal efnbodin1ent, the body Inay be .125 inoh long, .020 inoh thick and .oo inch vvide, Wif11the P type zone o2o inch thick. The thicknesS of the zone is of priIne n1oInent aS W1be pointed out hereinaftefb A difeot-ouffent biaSing souroe, Suoh as a battery 12, in sefies with a load l3 is connected between ohInic oonneotions of tefn1inals f4A and B, s11oh as oopper platingS, on the tWo I T type zones- ()I1e surface of the body, of a poftion thefeof, iS i11nn1inated ffofn a 1ight Soufoe l5, through aJ conoenffating lens lo. The faces of the body paftionlarly advantageously are treated to deofease the feoon1b1otion fate of e1eotfioa1 oaffiefs thefeato An especia1ly Satisfactory tTeatn1ent, diSolosed in detai1 in the appHoation Sefial1 No- 175, 648, filed July 2, 1950 of J. R. 11ayneS and R. 1). 1ieidenfeich, ooInprises oheInioaJlly po1ishing the suffaceS to a n1irTo' niSh in the n1anner desoribed in the application Serio1 1`To. 16 3o3, 1eo 1`ay 25 1950 of 1 D. feiden feich, now Patent 2 619,1, gTanted Noven1bef 25, 1952 and then Subjecting the Suffaces to o cataphofetio treatInent, vvith the gefn1aniun1 body e1eotrica11y positive felative to a ffletallio electrode, in an antimony oxychlofide soL n bfief, if1 the operation of the devioe, 1ight is absofbed by the gefInaniuIn body, fesolting in a deofease in the iInpedanoe betWeen the tef1ina1s 11 and aJ ooffeSponding inofeaSe i11 the cof- The cuffent is a funotion of the biaS voltage iInpfesSed betvveen the tefn1inalS and of the i11I1Inination intensity foWevef, it nlay be fefnfked here that t11e sensitivity is extrenlely high, ouffent ifloreaSes of the order of e1eo pendent in n1agnitude upon the oonoentfation of the n1inofity caffiers in the sevefa1 zones of the body. 1)esifably, thiS ooffent shou1d be SIfla11. 11ef1oe advantageous1y, the zoneS l0A and l0B afe fnade aS Strong1y N type af1d. the zone 11 is fnade aS Strong1y P type as osSib1e, oonsistenfly with the need foI' keeping the denSities of the dof1Of and acceptof impurities, Which Inay act aS feoofnbiflafion centefS and1ed fo shoftef carfief 1ifetin1eS, feasonably sfna11. The N type zone vVhich in pfaotice feoeiveS thB negative biaS (Shown in the gufeS aS the 1efthand zone) fnay advanta geouSly have a1ovV feSistivity, coffesponding to a 13fge denSity of eleoffonS avai1b1e fof conduotion into the P type layer when the bar fieI' is 1owered by light. In NPN gefnTaninm bodies fobfioated in acoofdance With the n1ethod disoloSed in the Tea1 app1ioation identified hefe inabove, and ino1uded in devioeS of the oonStfuo tiof1 Shovvn in 'ig. 1, `T ZneS have feSiStivitie of the ofdef of and 01 ohm oentiInetefS and a P zone having a fesiStivity of 1 ohn1 centimetef halve been found SatiSfaJotofy- Peffofn1anoe ohafotefiStioS of typioa1 photo Sensitive deviceS St1ch aS Shown in 1 ig. 1 and oon stfucted in acoofdance With thiS invention are inuStrated i11 gS. and 5. In both theSe g ureS, cuffent in fnillianlpefeS between the tef mina1S M is plotted againSt hiaSing voltage ap plied betWeen theSe tern1ifla1s, fof sevefa1 valueS of illuInination intenSity, the latter aTaIneter being indicated in foot oand1es on the individua1 ourves. 11So indicated in 1 'ig. 5 iS the 4000 ohff1 1oad 1if1e.

T11e thfee upper ourveS in 1 'ig, 4g fepfesent the ouffentvo1tage felationship fof i11ufflination of the entire surfaoe, the uppef Sufface in 1 ig. 1, of the senlioonductof body by a soufoe |5 of the intenSitieS designated. The oufveS of ig. 5 pof tray t11iS felationship fof the case Whefe the 1ight iS foouSSed upon the 1 zone and the in1 fnediately adjaoent fegions of the N zones by a lens 0, the 1111x intenSifies being those on the face of the lens 10, Whioh had 'alf1 afe of 01 Square inch. The 1ight souroe used for these fneaSufefnents Was a tungsfen fi1afflenf laJfT1p op efated at al oolof tefnpefatufe of 2 100 degfees abSolute.

t wi11 be noted frofn gs. and 5 that the fe SponSe is a function of both the i1111Inination and the biaSing voltage, f1 Pig. 5 if iS Seen that a 1ight nux of 6.2 f11i11i111InenS is suf1icient to ef feotive1 Wipe out the Nf N baffief, in Whioh caSe the curfent betvveen the eleotfodes M iS 1in1ffe(1 by the ohInic reSistance of the gerInaniufn in the ce11, in this oase aboot 220 ohInS. Pafticu1ar1y to be noted iS the high senSitivity. n typica1 devioes, ourfent incfeases of 100 eleotfons pef one ifloident phofon pef second have been ob tained.

0 A1though the invention has beef1 desofibed With pafticular Tefefenoe to geffnoniun1 devices and Such devices whefein a P zof1e is Sandwiohed betWeen a pair of 1T zoneS, it Inay be efnbodied a1So in si1ioon devioes and if1 phofoe1ectfic ce11S of either silicon of gefn1anium Whefein an N zone is Sandwiched betWeen tWo P zones. A1So, it vvi11 be undefStood that vafiouS fnodioationS Inay be made in the Specc embodiment ShoWn and deSofibed vvithout departing ffofn the scope and spifit of thiS invefltion.

vvhat1S olaifned iS:

1. f1 phofosenSitive devioe cofnpfising a body of Sen1ioonduotive fnatefia1 having thefein and extendin inWardl fron1 one face thereof a air of Zofios of one conductivity-typoS fafed by and oontiguous With 9 Zone of the opposite oon duotivity-fype, the thickneSS of the inteffflediate Zone being no greater fhan the diffusion 1ength of ohafge cafffs noffna1ly in fniflofity in Said inteffnediate zone, fneanS fof in1pfeSSing a biasing potentia1 betWeen said paif of zones, and n1eaf1S for difecting light against Said one faoe.

2.- 1L photoSef1Sitive device in acoofdanoe With claifn 1 conlpfising fneans fo1, ooncentfating the 1ight upon Said intefInediate zone.

3 A photoSensitive dev1oe in aocofdance With claifn 1 vvhefein said IT1atefial is gefn1aniun1.

1, A photosensitive devioe in acoofdanoe vvith olaifn 1 vvhefein said fnatefia1 is si1icon,

5. A photosenSitive devioe oofnpfisif1g a body of gefmanium having thefein and extending if1- wardly ffon1 one face thereof a pair of 1`T con duotivitytype zoneS Sepafated by and oontiguous With a zofle of P oonduotivityfype, the t11ickneSS of said Ptype zone being flo greater than aJ few tenthS ffli11ifnefef, feffnina1 connectionS to said 1`Ttype zof1es, a difect-ourrenf biasing soufce conneoted betWeen Said connectionS, and Ineans 111un1inating said face at said P zone.

6. f1 photosenSitive devioe conlpfising a Single ofySta1 body of geffnanium having af fniffof niSh face, said body having extending invvafdly ffon1 Said face a pair of N conductiv1t type zoneS oontiguous vvith and Sepafated by aJ P oonduo tivity-type zone, said Ptype Zone being no gfeate1' than a fevv tenthS Ini11inlefef in fhick I1esS, fneans fof app1ying a biaSing potentia1 be tWeen Said 1`Tfype zofles, and n1eanS for direot ing a conoentfated 1ight beam upon Said face of Said P type zone.

IeferenoeS cifed in the file of this patent UNITBD STATES PATNTS NuInber Name Date 2,02 662 oh1 June 25, 196 2,82,980 aHmnn sept. 27, 199 

